Organic light emitting display device and method of manufacturing the same

ABSTRACT

An organic light emitting display device includes a substrate and a plurality of pixels defined in the substrate. A pixel includes red subpixel, green subpixel, blue subpixel, and white subpixel. The organic light emitting display device includes an anode electrode formed on the substrate, a cathode electrode opposing the anode electrode, and a red common emission layer, a green common emission layer, and a blue common emission layer formed across each of the red, green, blue and white subpixel areas. The blue common emission layer is disposed above and adjacent to the anode electrode, the green common emission layer is disposed above the blue common emission layer, and the red common emission layer is disposed above the green common emission layer and adjacent to the cathode electrode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the Korean Patent ApplicationNos. 10-2012-0128572 filed on Nov. 14, 2012, and 10-2013-0057335 filedon May 21, 2013, which is hereby incorporated by reference as if fullyset forth herein.

BACKGROUND

1. Field of the Invention

The present invention relates to an organic light emitting displaydevice and a method of manufacturing the same.

2. Discussion of the Related Art

As a type of new flat panel display device, organic light emittingdisplay devices are self-emitting display devices, and have a betterviewing angle and contrast ratio than liquid crystal display (LCD)devices. Also, since the organic light emitting display devices do notneed a separate backlight, the organic light emitting display devicescan be made lighter and thinner with excellent power consumptioncompared to LCD devices and the other flat panel display devices.Furthermore, the organic light emitting display devices are driven witha low direct current (DC) voltage, have a fast response time, and arelow in manufacturing cost.

In organic light emitting display devices, an electron and a hole arerespectively injected from a cathode and an anode into an emittingmaterial layer, and, when an exciton in which the injected electron andhole are combined is shifted from an excited state to a base state,light is emitted. In this case, the types of organic light emittingdisplay devices are categorized into a top emission type, a bottomemission type, and a dual emission type according to an emissiondirection of light, and categorized into a passive matrix type and anactive matrix type according to a driving type.

Specifically, the organic light emitting display device includes a firstelectrode (anode), a hole transporting layer, an emitting material layerincluding a red organic emission pattern, a green organic emissionpattern, and a blue organic emission pattern, an electron transportinglayer, and a second electrode (cathode), which are formed in each of ared pixel area, a green pixel area, and a blue pixel area.

In the organic light emitting display devices having such structure,when a voltage is applied to the first and second electrodes, a holemoves to the emitting material layer through the hole transportinglayer, an electron moves to the emitting material layer through theelectron transporting layer, and the hole and the electron are combinedin the emitting material layer, thereby emitting light.

In the organic light emitting display devices, a fine metal mask (FMM)process is used for patterning the emitting material layer between twoelectrodes disposed on a substrate. Numerous FMM processes may beperformed to manufacture an organic light emitting display device. WhenFMM processes are applied to different pixels, a fine metal mask needsto be moved and aligned for different pixels. During that process, thefine metal mask may not be properly aligned which may cause certaindefects. Also, each FMM process may require alignment of a mask overdifferent pixels of an organic light emitting display device. Suchalignment may require substantial time and labor, which addsmanufacturing expenses and lengthens manufacturing time. Moreover, amask used in FMM processes is costly. Accordingly, there is a need toreduce a number of FMM process and simplify manufacturing processes.

SUMMARY

Accordingly, an organic light emitting display device and a method ofmanufacturing the same that substantially obviate one or more problemsdue to limitations and disadvantages of the related art may be provided.

An aspect of the present invention is directed to a high-efficiencywhite organic light emitting display device (WOLED) that has a structurewhich emits red, green, blue, and white light by forming red, green, andblue emitting material layers as a common layer, realizes excellentlight output efficiency, maintains a color characteristic, and enablesthe simplification of a process and the saving of the manufacturingcost.

Additional advantages and features of the invention will be set forth inpart in the description which follows and in part will become apparentto those having ordinary skill in the art upon examination of thefollowing or may be learned from practice of the invention. Theobjectives and other advantages of the invention may be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the invention, as embodied and broadly described herein, An organiclight emitting display device includes a substrate and a plurality ofpixels defined in the substrate. A pixel includes red subpixel, greensubpixel, blue subpixel, and white subpixel. The organic light emittingdisplay device includes an anode electrode formed on the substrate, acathode electrode opposing the anode electrode, and a red commonemission layer, a green common emission layer, and a blue commonemission layer formed across each of the red, green, blue and whitesubpixel areas. The blue common emission layer is disposed above andadjacent to the anode electrode, the green common emission layer isdisposed above the blue common emission layer, and the red commonemission layer is disposed above the green common emission layer andadjacent to the cathode electrode.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiments of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a conventional organic light emitting display device;

FIGS. 2A to 2D are views illustrating an energy band diagram of anorganic light emitting display device according to one embodiment of thepresent invention; and

FIGS. 3 to 6 are sectional views schematically illustrating organiclight emitting display devices according to a comparative example and anexample.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings. Like referencenumerals refer to like elements throughout. In the followingdescription, when the detailed description of the relevant knownfunction or configuration is determined to unnecessarily obscure theimportant point of the present invention, the detailed description isnot provided.

FIG. 1 is a sectional view schematically illustrating an organic lightemitting display device according to one embodiment of the presentinvention. As illustrated in FIG. 1, the organic light emitting displaydevice includes a first electrode (anode) 110, a hole injection layer120, a first hole transporting layer 130, a blue common emission layer142, a second hole transporting layer 132, a first electron transportinglayer 150, a green common emission layer 144, a third hole transportinglayer 134, a second electron transporting layer 152, a red commonemission layer 146, a third electron transporting layer 154, a secondelectrode (cathode) 160, and a capping layer 170 that are sequentiallyapplied on a substrate (not shown) in which red, green, blue, and whitepixel areas Rp, Gp, Bp and Wp are defined.

Although not shown, in the organic light emitting display device, aplurality of gate lines and a plurality of data lines, which define aplurality of pixel areas Rp, Gp, Bp and Wp by intersectionstherebetween, and a plurality of power lines that extend parallel torespective corresponding lines among the gate lines and the data linesare disposed on the substrate (not shown). A switching thin filmtransistor (TFT) connected to a corresponding gate line and data lineand a driving TFT connected to the switching TFT are disposed in each ofthe pixel areas Rp, Gp, Bp and Wp. Here, the driving TFT is connected tothe first electrode 110.

In an embodiment, the organic light emitting display device includes anorganic layer between the first electrode 110 and the second electrode160 facing the first electrode 110, the hole injection layer 120, thefirst hole transporting layer 130, the second hole transporting layer132, the third hole transporting layer 134, the blue common emissionlayer 142, the green common emission layer 144, the red common emissionlayer 146, the first electron transporting layer 150, the secondelectron transporting layer 152, and the third electron transportinglayer 154.

The first electrode 110 is formed in a plate shape in the red, green,blue, and white pixel areas Rp, Gp, Bp and Wp, in the substrate (notshown). The first electrode 110 is a reflective electrode, and forexample, may have a multi-layer structure that includes a transparentconductive material layer (having a high work function) such as indiumtin oxide (ITO) and a reflective material layer such as Ag or an Agalloy.

The hole injection layer 120, the first hole transporting layer 130, andthe blue common emission layer 142 are formed on the first electrode 110in respective positions corresponding to the red, green, blue, and whitepixel areas Rp, Gp, Bp and Wp. The first hole transporting layer 130 maybe called a common layer, and the hole injection layer 120 may not beprovided. A thickness of the hole injection layer 120 and first holetransporting layer 130 may be about 10 to 50 nm, but may be adjusted inconsideration of a hole injection characteristic and a hole transportcharacteristic.

The second hole transporting layer 132 is formed on the blue commonemission layer 142 at a position corresponding to the green pixel areaGp. That is, the second hole transporting layer 132 is formed betweenthe blue common emission layer 142 and the green common emission layer144. A thickness of the second hole transporting layer 132 may be about50 to 100 nm, but may be adjusted in consideration of a hole transportcharacteristic. Alternatively, the second hole transporting layer 132may not be provided.

The third hole transporting layer 134 is formed on the green commonemission layer 144 at a position corresponding to the red pixel area Rp.That is, the third hole transporting layer 134 is formed between thegreen common emission layer 144 and the red common emission layer 146. Athickness of the third hole transporting layer 134 may be about 100 to200 nm, but may be adjusted in consideration of a hole transportcharacteristic. Alternatively, the third hole transporting layer 134 maynot be provided.

In one embodiment, a thickness of the third hole transporting layer 134may be greater than that of the second hole transporting layer 132, butthe thickness of the third hole transporting layer 134 is not limitedthereto.

An emitting material layer including the blue common emission layer 142,the green common emission layer 144, and the red common emission layer146 is formed at a position corresponding to the red, green, blue, andwhite pixel areas Rp, Gp, Bp and Wp. That is, the emitting materiallayer is formed as a common layer in each of the pixel areas includingthe white pixel areas Wp, and thus may be formed even without a finemetal mask (FMM).

In one embodiment, the blue common emission layer 142 is formed on thefirst hole transporting layer 130. The green common emission layer 144is formed on the blue common emission layer 142, the second holetransporting layer 132 that is disposed at a position corresponding tothe green pixel area Gp, and the first electron transporting layer 150that is disposed at position corresponding to the blue pixel area Bp.The red common emission layer 146 is formed on the green common emissionlayer 144 that are disposed at respective positions corresponding to theblue and white pixel areas Bp and Wp, the third hole transporting layer134 that is disposed at a position corresponding to the red pixel areaRp, and the second electron transporting layer 152 that is disposed at aposition corresponding to the green pixel area Gp. A thickness of theblue, green, and red common emission layers 142, 144 and 146 may beabout 10 to 50 nm, but may be adjusted in consideration of an emissioncharacteristic.

The first electron transporting layer 150 is formed on the blue commonemission layer 142 at a position corresponding to the blue pixel areaBp. That is, the first electron transporting layer 150 is formed betweenthe blue common emission layer 142 and the green common emission layer144. A thickness of the first electron transporting layer 150 may beabout 10 to 50 nm, but may be adjusted in consideration of an electrontransport characteristic. Alternatively, the first electron transportinglayer 150 may not be provided.

The second electron transporting layer 152 is formed on the green commonemission layer 144 at a position corresponding to the green pixel areaGp. That is, the second electron transporting layer 152 is formedbetween the green common emission layer 144 and the red common emissionlayer 146. A thickness of the second electron transporting layer 152 maybe about 10 to 50 nm, but may be adjusted in consideration of anelectron transport characteristic. Alternatively, the second electrontransporting layer 152 may not be provided.

The third electron transporting layer 154 is formed on the red commonemission layer 146 at a position corresponding to the red, green, blue,and white pixel areas Rp, Gp, Bp and Wp, and thus may be called a commonlayer. A thickness of the third electron transporting layer 154 may beabout 25 to 35 nm, but may be adjusted in consideration of an electrontransport characteristic. The third electron transporting layer 154 mayact as an electron transport and injection layer, but an electroninjection layer may be separately formed on the third electrontransporting layer 154.

The second electrode 160 is formed on the third electron transportinglayer 154. For example, the second electrode 160 is formed of an alloy(Mg:Ag) of Mg and Ag, and has semi-transmissive characteristic. That is,light emitted from the red, green, and blue common emission layers istransferred to the outside through the second electrode 160, in whichsome of the light is again transferred to the first electrode 110because the second electrode 160 has a semi-transmissive characteristic.

Therefore, repetitive reflection is performed between the firstelectrode 110 (acting as a reflective electrode) and the secondelectrode 160. This is called the micro-cavity effect. That is, light isrepeatedly reflected in a cavity between an anode (which is the firstelectrode 110) and a cathode that is the second electrode 160, therebyincreasing light efficiency.

In this case, light respectively emitted from the blue, green, and redcommon emission layers 142, 144 and 146 has different wavelengths, andthus, a thickness “d” of a cavity defined as a distance between thefirst and second electrodes 110 and 160 is differently set. That is, thethickness “d” of the green pixel area Gp is less than that of the redpixel area Rp that emits red light having the longest wavelength, andgreater than that of the blue pixel area Bp that emits blue light havingthe shortest wavelength. Also, to emit white light, the white pixel areaWp has a thickness less than the blue pixel area Bp.

In the present invention, a thickness in each pixel area, namely, adistance between the first and second electrodes 110 and 160 can bevaried by adjusting the respective thicknesses of the second and thirdhole transporting layers 132 and 134, and the first and second electrontransporting layers 150 and 152. As a result, in the present invention,the thickness of the third hole transporting layer 134 is greater thanthe sum of thicknesses of the second hole transporting layer 132 andsecond electron transporting layer 152, and the thickness of the firstelectron transporting layer 150 is less than the sum of thicknesses ofthe second hole transporting layer 132 and second electron transportinglayer 152.

The capping layer 170 increases a light extraction effect, and may beformed of one of materials of the first to third hole transportinglayers 130, 132 and 134, materials of the first to third electrontransporting layer 150, 152 and 154, and host materials of the blue,green, and red common emission layers 142, 144 and 146. Alternatively,the capping layer 170 may not be provided.

As described above, the organic light emitting display device accordingto one embodiment of the present invention maintains light outputefficiency and color characteristic, and simultaneously realizes ahigh-quality image.

Meanwhile, to form a material pattern in each of the pixel areas Rp, Gp,Bp and Wp, the FMM having an opening is used in correspondence with eachpixel area. In this case, processes using the FMM in separate chambersare needed for forming the second and third hole transporting layers 132and 134 and the first and second electron transporting layer 150 and 152that have different thicknesses.

First, the first electrode 110 is formed, and then, the hole injectionlayer 120 and the first hole transporting layer 130 are formed withoutthe FMM in a first chamber. The hole injection layer 120 may be formedby doping a P-type dopant, for example, boron (B) into the material ofthe first hole transporting layer 130. Subsequently, the blue commonemission layer 142 is formed of a blue organic material with no FMM in asecond chamber.

Subsequently, the second hole transporting layer 132 is formed in thegreen pixel area Gp using a first FMM in a third chamber. The secondhole transporting layer 132 may be formed by doping the P-type dopant,for example, boron (B) into the material of the first hole transportinglayer 130. Subsequently, the third hole transporting layer 134 is formedin the blue pixel area Bp using a second FMM in a fourth chamber. Thethird hole transporting layer 134 may be formed by doping an N-typedopant, for example, phosphorous (P) into the material of the thirdelectron transporting layer 154. Subsequently, the green common emissionlayer 144 is formed of a green organic material with no FMM in a fifthchamber.

Subsequently, the third hole transporting layer 134 is formed in the redpixel area Rp using a third FMM in a sixth chamber. The third holetransporting layer 134 may be formed by doping the P-type dopant, forexample, boron (B) into the material of the first hole transportinglayer 130. Subsequently, the second electron transporting layer 152 isformed in the green pixel area Gp using a fourth FMM in a seventhchamber. The second electron transporting layer 152 may be formed bydoping the N-type dopant, for example, phosphorous (P) into the materialof the third electron transporting layer 154.

Subsequently, the red common emission layer 146 is formed of a redorganic material with no FMM in an eighth chamber. Finally, the thirdelectron transporting layer 154, the second electrode 160, and thecapping layer 170 are sequentially formed with no FMM in ninth toeleventh chambers, respectively.

That is, processes may be performed using four FMMs in a total of elevenchambers, for implementing the micro-cavity structure. As describedabove, the organic light emitting display device according to oneembodiment of the present invention can solve problems due to adefective mask, simplify a process, and save the manufacturing cost.

FIGS. 2A to 2D are views illustrating an energy band diagram of anorganic light emitting display device according to one embodiment of thepresent invention. Here, FIG. 2A is a view illustrating red emission,FIG. 2B is a view illustrating green emission, FIG. 2C is a viewillustrating blue emission, and FIG. 2D is a view illustrating whiteemission.

Generally, a hole is injected from the first electrode 110, and anelectron is injected from the second electrode 160. Thus, the hole andthe electron are combined to form an axciton in an emission layer, andwhen the axciton is shifted from an excited state to a base state, lightcorresponding to energy is emitted as visible light.

As illustrated in FIG. 2A, the hole injected from the first electrode110 and the electron injected from the second electrode 160 are combinedto form the exciton in the red common emission layer 146, therebyemitting red light. At this time, since transfer of the electroninjected from the second electrode 160 is completely prevented by thethird hole transporting layer 134, light is not emitted from the greencommon emission layer 144 or the blue common emission layer 142, andonly the red common emission layer 146 emits light.

As illustrated in FIG. 2B, the hole injected from the first electrode110 and the electron injected from the second electrode 160 are combinedto form the exciton in the green common emission layer 144, therebyemitting green light. At this time, since transfer of the electroninjected from the second electrode 160 is completely prevented by thesecond hole transporting layer 132 and transfer of the hole injectedfrom the first electrode 110 is completely prevented by the secondelectron transporting layer 152, light is not emitted from the redcommon emission layer 146 or the blue common emission layer 142, andonly the green common emission layer 144 emits light.

As illustrated in FIG. 2C, the hole injected from the first electrode110 and the electron injected from the second electrode 160 are combinedto form the exciton in the blue common emission layer 142, therebyemitting blue light. At this time, since transfer of the hole injectedfrom the first electrode 110 is completely prevented by the firstelectron transporting layer 150, light is not emitted from the redcommon emission layer 146 or the green common emission layer 144, andonly the blue common emission layer 142 emits light.

As illustrated in FIG. 2D, the hole injected from the first electrode110 and the electron injected from the second electrode 160 are combinedto simultaneously form the exciton in the common emission layers,namely, the blue common emission layer 142, the green common emissionlayer 144, and the red common emission layer 146, thereby emitting whitelight. At this time, since the hole injected from the first electrode110 and the electron injected from the second electrode 160 are notprevented in transfer, and all of the common emission layers emit light.

To provide a detailed description, an energy band gap of the greencommon emission layer is greater than that of the red common emissionlayer, and less than that of the blue common emission layer. That is, anelectron and a hole are first combined to emit light in a layer having abroad energy band gap, and then, when an electron and a hole are againcombined in a layer having an energy band gap narrower than the broadenergy band gap, light may be emitted. However, an electron and a holeare first combined to emit light in a layer having a narrow energy bandgap, and then, when an electron and a hole are again combined in a layerhaving an energy band gap broader than the narrow energy band gap, lightcannot be emitted.

Therefore, as in the red pixel area Rp of FIG. 1, in a structure inwhich the blue common emission layer, the green common emission layer,the third hole transporting layer, and the red common emission layer aresequentially stacked between the first and second electrodes 110 and160, an electron and a hole are combined to emit light in the red commonemission layer, and then, as electron transfer is prevented in the thirdhole transporting layer, light is not emitted from the green and bluecommon emission layers.

Moreover, as in the green pixel area Gp of FIG. 1, in a structure inwhich the blue common emission layer, the second hole transportinglayer, the green common emission layer, the second electron transportinglayer, and the red common emission layer are sequentially stackedbetween the first and second electrodes 110 and 160, an electron and ahole are combined to emit light in the green common emission layer, andthen, light is not emitted from the blue common emission layer having abroad energy band gap.

Moreover, as in the blue pixel area Bp of FIG. 1, in a structure inwhich the blue common emission layer, the first electron transportinglayer, the green common emission layer, and the red common emissionlayer are sequentially stacked between the first and second electrodes110 and 160, an electron and a hole are combined to emit light in theblue common emission layer, and then, as hole transfer is prevented inthe first electron transporting layer, light is not emitted from thegreen and red common emission layers.

Moreover, as in the white pixel area Wp of FIG. 1, in a structure inwhich the blue common emission layer, the green common emission layer,and the red common emission layer are sequentially stacked between thefirst and second electrodes 110 and 160, an electron and a hole arecombined to emit light in all of the common emission layers.

FIGS. 3 to 6 are sectional views schematically illustrating organiclight emitting display devices according to a comparative example and anexample. Here, FIG. 3 illustrates a structure of a comparative example1, FIG. 4 illustrates a structure of an example 2, FIG. 5 illustrates astructure of an example 3, and FIG. 6 illustrates a structure of anexample 4.

First, Table 1 compares color coordinates and efficient characteristicof a comparative example 1 (the organic light emitting display device ofFIG. 3) with color coordinates and efficient characteristic of anexample 1 (the organic light emitting display device of FIG. 1).

That is, a comparative example 1 having the following structure isevaluated for comparing the characteristic of the organic light emittingdisplay device according to an embodiment (example 1) of the presentinvention. A comparative example 1 has a structure in which white lightis emitted using a red color filter (red C/F), a green color filter(green C/F), and a blue color filter (blue C/F).

TABLE 1 Efficient characteristic (cd/A) of R G B W Structure OLED cd/A xy cd/A x y cd/A x y cd/A x y Comparative 22.5 6.10 0.667 0.328 24.10.277 0.667 2.4 0.143 0.058 74 0.342 0.383 example 1 Example 1 24.5 55.00.662 0.336 110.0 0.287 0.685 5.5 0.143 0.045 26 0.311 0.400

As shown in Table 1, it can be seen that there is hardly a colorcharacteristic difference between the organic light emitting displaydevice (example 1) according to one embodiment of the present inventionand a comparative example 1, and an efficient characteristic of theorganic light emitting display device (example 1) according to oneembodiment of the present invention is improved compared to acomparative example 1.

Next, Table 2 compares color coordinates and efficient characteristicsof a comparative example 1 (the organic light emitting display device ofFIG. 3) and examples 2 to 4 (the organic light emitting display devicesof FIGS. 4 to 6).

TABLE 2 Efficient characteristic (cd/A) R G B W Structure of OLED cd/A xy cd/A x y cd/A x y cd/A x y Comparative 22.5 6.1 0.667 0.328 24.1 0.2770.667 2.4 0.143 0.058 74 0.342 0.383 example 1 Example 2 40.2 55 0.6620.336 110 0.287 0.685 5.5 0.143 0.045 55 0.304 0.407 Example 3 38.4 550.662 0.336 110 0.287 0.685 5.5 0.143 0.045 50 0.312 0.399 Example 449.8 55 0.662 0.336 110 0.287 0.685 5.5 0.143 0.045 80 0.307 0.404

As shown in Table 2, it can be seen that there is hardly a colorcharacteristic difference between the organic light emitting displaydevices (examples 2 to 4) according to another embodiment of the presentinvention and a comparative example 1, and efficient characteristics ofthe organic light emitting display devices (examples 2 to 4) accordingto another embodiment of the present invention are improved compared toa comparative example 1.

Therefore, although the red, green, and blue common emitting materiallayers are stacked as a common layer, the organic light emitting displaydevice according to one embodiment of the present invention can maintaina color characteristic and realize a high-quality and high-efficiencyimage.

In the specification, a top emission type organic light emitting displaydevice (OLED) has been exemplified, but the spirit and scope of thepresent invention are not limited thereto. The present invention may beapplied to organic light emitting display devices having various typessuch as a bottom emission type, a dual emission type, a tandem type,etc.

As described above, by realizing the structure which emits red, green,blue, and white light by forming the red, green, and blue emittingmaterial layers as the common layer, the present invention realizesexcellent light output efficiency, and maintains a color characteristic.That is, it is not required to form a separate emitting material layerin each pixel area, and thus, the emitting material layer is formedwithout using an FMM. Accordingly, color mixture is prevented,limitations due to a defective mask are overcome, a process issimplified, and the manufacturing cost is saved.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. An organic light emitting display device,comprising: a substrate; a plurality of pixels defined in the substrate,a pixel comprising red subpixel, green subpixel, blue subpixel, andwhite subpixel, the pixel further comprising: an anode electrode formedon the substrate; a cathode electrode opposing the anode electrode; ared common emission layer, a green common emission layer, and a bluecommon emission layer formed across each of the red, green, blue andwhite subpixel areas, wherein the blue common emission layer is disposedabove and adjacent to the anode electrode, the green common emissionlayer is disposed above the blue common emission layer, and the redcommon emission layer is disposed above the green common emission layerand adjacent to the cathode electrode; wherein the red common emissionlayer, the green common emission layer, and the blue common emissionlayer stacked in the white subpixel emits a red light, a green light,and a blue light such that a white light is output from the whitesubpixel.
 2. The organic light emitting display device of claim 1,wherein the red subpixel comprises an electron blocking layer betweenthe green common emission layer and the red common emission layer. 3.The organic light emitting display device of claim 1, wherein the greensubpixel comprises an electronic blocking layer between the blue commonemission layer and the green common emission layer and a hole blockinglayer between the green common emission layer and the red commonemission layer.
 4. The organic light emitting display device of claim 1,wherein the blue subpixel comprises a hole blocking layer between theblue common emission layer and the green common emission layer.
 5. Theorganic light emitting display device of claim 1, wherein the red commonemission layer, the green common emission layer, and the blue commonemission layer are sequentially stacked in the white subpixel withouthaving an electronic blocking layer and a hole blocking layer.
 6. Theorganic light emitting display device of claim 1, further comprising ahole injection layer and a hole transporting layer between the anodeelectrode and the blue common emission layer.
 7. The organic lightemitting display device of claim 1, wherein a thickness of layersstacked in the red subpixel between the anode electrode and the cathodeelectrode differs from at least one of thickness of layers stacked inthe blue, green, or white subpixels between the anode electrode and thecathode electrode.
 8. The organic light emitting display device of claim1, further comprising a capping layer on the cathode electrode.